January 6, 2023

The technical secrets behind Audi’s ‘electric’ Dakar challenger

Audi Sport’s project for the 2022 Dakar Rally is something so unique that it brought all its departments together to work on it. Despite the COVID-19 pandemic, which prevented the crew from returning home for several months, the team led by Andreas Roos presented the RS Q e-tron 4×4 hybrid on July 23, more than five months ahead of its Dakar debut.

The prototype with which Carlos Sainz, Stephane Peterhansel and Mattias Ekstrom will attempt to score a first Dakar win for a car with alternative propulsion is “enormously complex”, as several key people working on the project explained to Motorsport.com/Autosport.

The idea, which Audi Sport began to develop on in August 2020, involves using the MGU it developed for its final season in Formula E to power its two axles, and to charge the batteries (13 modules of 266 cells each, storing 52 kWh of power and weighing 375 kg).

In addition, the 2.0 turbocharged four-cylinder combustion engine derived from the DTM will be responsible for recharging the batteries via a third MGU, which will also act as a converter of kinetic energy into electrical energy. Energy generated under braking will also be used to recharge the battery.

The presence of a petrol engine and a 295-litre fuel tank means that the project is not 100% electric, but in order to be able to complete 700km a day in the middle of the desert, the German brand has had to resort to this technical trickery. The presence of both electric motors and a conventional combustion engine has made the prototype even more complex, and it’s something that has never been tested before in competition, especially in extreme conditions such as those of the Dakar.

How the drivers will manage the recharging of batteries

Audi RS Q e-tron steering wheel

Photo by: Audi

While the project’s managers made it clear that there are still many details to be decided and software configurations are yet to be finalised, they provided some key insights into how this hybrid beast will be managed across the sands of the Saudi Arabian desert from January 1, 2022. 

Drivers will have one brake pedal and one accelerator pedal, although there will be no gear shifter or clutch pedal, as the prototype has a single-gear gearbox for each of its axles. 

In the first onboard footage from the opening week of testing, it can be seen how the drivers do not take their hands off the wheel at any time, which is very different to the ‘dance’ of a traditional rally or cross-country driver. 

Pressure on the throttle will activate the front and rear MGUs and move the two axles (not mechanically connected to each other) to achieve a maximum power output of around 300kW (400bhp, yet to be specified by FIA regulations).

The role of the central differential will be “virtual” (there is no mechanical part as such), distributing torque between the front and rear axles as required. In addition, the limited-slip differentials will be managed electronically.

“The combustion engine won’t be running at all times,” Roos tells Motorsport.com. “It will only kick in to recharge the battery when the software detects that this is the best time and at around 4,500-6,000rpm to be as efficient as possible. 

“We are defining at what percentage of battery drain it will kick in, but what is clear is that it will not be at 100 percent because it would not be efficient to keep the battery at those levels at all times.”

Audi Sport is working on some sort of “driving modes” (remotely similar to the marque’s road cars) so that drivers can decide when to use maximum power (for example, if the roadbook indicates a straight stretch of several kilometres with no dangers), but the approach is for the processes inside the RS Q e-tron tech to be as automated as possible. 

Audi also plans to recharge its batteries via plug-in in the Dakar bivouac with a system “as green as possible”, but that is still in discussions with ASO, the organiser of the rally.

The most complex part of the car

Audi RS Q e-tron

Audi RS Q e-tron

Photo by: Audi

When asked what is the most complex part and the one that has given it the most headaches in recent months, Sven Quandt, the head of Audi’s partner Q Motorsport, and Andreas Roos unanimously agree that it’s the software used on the car.

The RS Q e-tron has no less than four kilometres of wiring and a number of computers that will be responsible, for example, for acting as a link between the battery and the MGU, between the TFSI combustion engine and the battery, and all of these components with the dashboard inside the cockpit.

“I compare it to the moon landing mission – at that time the engineers were not quite sure what the next steps would be,” said Quandt, who won the Dakar six times as team manager.

“It’s something similar for us, because every week of work we have discovered new challenges. 

“Everyone knows how often you have to reset a computer. The car is very complex with all its components. They all have to communicate with each other. 

“It’s like putting 12 people in a room, each of whom speaks a different language, but they are all supposed to be working on the same task. Incredibly large amounts of data is exchanged between the different components. From [one] MGU to [another] MGU, from the battery to the engines and also to the power converter. That makes it very complex”.

Another key issue for any Dakar project is reliability, and even more so for a newborn prototype that relies so heavily on connections and cables. 

“Reliability is the first priority,” said Stefan Dreyer, head of technical development at Audi Sport. “Actually, there is no component that gives me a particular headache. It’s more the fact that we are developing such a complex project under pandemic conditions in just 12 months.

“Even before this project started we asked ourselves what a powertrain system would look like in the future of motorsport. 

“We have already achieved an efficiency of over 97% in Formula E; there is not much more room for improvement. But the situation is quite different with the battery and energy management. 

“This is where the greatest potential for development lies. What we learn from the demanding Dakar project will carry over to future road production models, I’m sure.

“Our dream is to become the first manufacturer to win the Dakar with an alternative powertrain.”

Audi RS Q e-tron

Audi RS Q e-tron

Photo by: Audi

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